Alerts and modal windows not masking entire HTML body

When I throw up an Ext.msg.Alert or Ext.window.Window with modal set to true, the entire document does not get masked. Only the available width and height that existing BEFORE all my elements were rendered gets masked. Anything that renders beneath this virtual boundary is still available for interaction with by users.

Screen capture below.

Is there any way to force the boundary to be the entire height/width of the HTML document?